You'd pick Quart because it's the largest measure and is about the same size (a pitcher might be 2 quarts, for example). You might pick one of the others if your purpose in measuring the lemonade was to determine how you're going to use it. So, if you're doling it out in a tiny cup size: Ounce; small mug - Cup; big mug - Pint; 7-11 Big Gulp - Quart.